Prospective randomized study in cemented primary total knee arthroplasty. In one group the cement used was standard cement, without any antibiotics and in the other group the cement used was loaded with 0.5 g of erythromycin and 3 million units of colistin in 40 g of cement. In all cases intravenous antibiotics prophylaxis against infection was used. In both groups the cement was mechanically mixed in a vacuum. One deep drain tube was placed for 24 hours in all cases. The main variable was the presence of infection according to the Center of Disease Control criteria with a minimum of 12 months follow-up.

Inclusion Criteria:

• Primary total knee replacement. Both genders. No age limits.

Exclusion Criteria:

• Allergy to erythromycin or colistin. Previous infection in the knee.